A variety of pesticides have been developed and used in many fields. Sustained release of a pesticidally active ingredient from a pesticidal composition into soil, water, or another specific environment allows sustainable effects of the pesticide on target pest and reduces the phytotoxicity of the composition on plants. Irrespective of wide researches and investigations, however, any method of realizing sufficient sustained release of a pesticidally active ingredient has not been found yet.